A British man has reportedly been detained in Mauritania amid reports that he was trying to join up with an Islamic terror group in the Sahara desert.

The man was reportedly held on the border between Mauritania and Mali as he attempted to cross the v [PA]

The Foreign Office (FCO) said they are investigating reports that a British national had been detained in the African country.

The man was reportedly held on the border between Mauritania and Mali as he attempted to cross the vast Sahara desert on foot to join up with terrorists linked to al Qaida in the Islamic Maghreb (AQIM).

An FCO spokeswoman said: "We are aware of reports of the detention of a British National in Mauritania and are seeking further information."

Islamists have seized control of northern Mali, including the ancient desert city of Timbuktu.

They have imposed Sharia law, carried out public executions, stoned to death a couple accused of adultery and destroyed mausoleums listed as world heritage sites.

In one case a 15-year-old girl received 60 lashes after the Ansar Dine extremists convicted her of speaking to men on the street.

South African Stephen McGown was reportedly kidnapped by Islamists in Timbuktu in November 2011 and is still being held hostage.

The extremists are demanding the release of radical preacher Abu Qatada in return for the release of Mr McGown, according to reports.

This month, the UN Security Council approved an African-led military operation to oust the Islamists in northern Mali. The country was plunged into turmoil in March after a coup in the capital of Bamako created a security vacuum.